Chances are, you have fewer friends than most of your friends have. It might seem strange, but that's true for almost all of us. The phenomenon is called the "friendship paradox," and it's a mathematical pattern that underlies many of life's little annoyances.

Steven Strogatz explains on The New York Times our perception is skewed by weighted averages, counting not just the number being averaged but also the relative importance of each number. For example, for two classes, one with 90 students in it and the other with 10, the average class size should be 50, because (90 + 10)/2 = 50. However, most students (90 out of 100) would think the average class size is larger than 50 because many more of them experience the 90-student class.

This is the same phenomenon at work when you go to the gym and feel everyone else is more fit than you are (the gym skews towards gym rats) or when you think public places seem to be more crowded than the average would suggest.

When it comes to friendship and social networks, popular friends "contribute disproportionately to the average, since besides [having more friends], they're named as friends more frequently." Strogatz cites a recent study that examined 721 million Facebook users and found that a user's friend count was less than the average friend count of his/her friends 93 percent of the time. The theory is that the average number of "friends of friends" will always be greater than the average number of friends of individuals, because the more popular people are counted more than once.

So don't worry if it seems like your friends are more popular than you are. We're all in the same boat.